In the field of lighting technology, the development trends for light sources are low cost, environmental friendliness, and power saving in order to acquire better lighting performance under the condition of consuming less power. These trends make LEDs play an important role in the development.
Practically, there are still limitations and challenges for applying LEDs or similar light emitting units to lamps for lighting. In the past, using LEDs as a light source called for depositing multiple LED chips on a plane and further providing an optical reflection mechanism to guide or broadcast the light emitted from the LED chips emitting light directionally in the beginning.
This kind of arrangement described above was not appropriate to substitute for traditional lamps with wide lighting angles. Because only a portion of light generated by the LED chips propagated in the direction of lighting while the other portions were absorbed or lost during the reflection processes, the lighting efficiency was low and the number of the LED chips must be increased for compensation and meeting the brightness requirement for lighting. Therefore the cost of the tradition LED lamp was high and the benefit for saving energy was insufficient.
Moreover, in traditional LED lamps, the substrates on which LED chips were deposited were planar, firm, and opaque. Thereby, the flexibility of disposing LED chips was limited. For example, when the substrates were non-planar, the light generated by the LED chips deposited on the substrates would be shielded or blocked accordingly, which was unfavorable for reducing power consumption and costs of traditional LED lamps.